Null Check Analysis

Null dereferencing is one of the most frequent bugs in Java systems causing programs to crash due to the uncaught NullPointerException. Developers often fix this bug by introducing a guard (i.e., null check) on the potentially-null objects before using them. In this paper we investigate the null checks in 717 open-source Java systems to understand when and why developers introduce null checks. We find that 35 of the if-statements are null checks. A deeper investigation shows that 71 of the checked-for-null objects are returned from method calls. This indicates that null checks have a serious impact on performance and that developers introduce null checks when they use methods that return null.

Failure or Voluntary Exit? Reassessing the Female Underperformance Hypothesis

We reevaluate the female underperformance hypothesis by challenging the assumption that female-owned ventures are more likely to fail. Instead of equating exit with failure, we draw on exit literature and feminist theories to argue that female entrepreneurs are actually more likely than males to exit voluntarily. We argue for further gender differences by using an even more fine-grained conceptualization of entrepreneurial exit (failure, exit for personal reasons, and exit for other professional/financial opportunities). Post-hoc analyses also point to withingender heterogeneity depending on family status. A sample probe of 219 Spanish entrepreneurs who had exited their business supports our overall reasoning.

Tri-level study: modification. Task 6: a final report on supplemental causation assessments through hypothesis testing.

National Highway Traffic Safety Administration, Washington, D.C.

Irritation and counterirritation, a hypothesis about the autoamputative property of the nervous system; a scientific excursion into theoretical medicine.

Mode of access: Internet.

Testing the expectations hypothesis when interest rates are near integrated /

Mode of access: Internet.

Rayos de la luz practica con que Don Feliz Pacheco Ortiz ... desvanece las sombras con que el Doctor Don Francisco Sanz ... intento obscurecer la Hypothesis de fiebres del Doctor Don Martin Martinez ... y haze resplandecer la particular Hypothesis y debida curacion de la fiebres intermitentes del Doctor Don Luis Enriquez ...

Discurso previo apologetico sobre el constitutivo de la calentura, a favor de ... Martin Martinez y contra ... Francisco Saenz de los Rios ... escrito por ... Francisco Valles de p. 2¶2 a 4¶3.

The performance of the null-reference glide-slope system in presence of deep snow, 1975-1976 /

Mode of access: Internet.

Why I think so; the autobiography of a hypothesis

"Errata" slip inserted between p. 44 and 45.

Application of the hypothesis of dissolved ice to the freezing of water and of dilute solutions.

Hudson, C.S., cl. of 1901.

An illustration of the hypothesis proposed in the dissertation on the origin and composition of our three first canonical gospels : with a preface, and an appendix, containing miscellaneous matters. The whole being a rejoinder to the anonymous author of the remarks on Michaelis and his commentator.

Mode of access: Internet.

An hypothesis which may help to unfold the mystery of Ezekiel's visions; accounting for the form and number of the four creatures, why different from those in the Apocalypse, why they are seen to issue out of the cloud, the reason why wheels were introduced, why they work as a wheel within a wheel, with many particulars unexplained before.

Mode of access: Internet.

The late Mrs. Null /

Mode of access: Internet.

An outline of a one semester course on distribution-free statistical inference: hypothesis testing (as given at Columbia University, Autumn 1958)

Mode of access: Internet.

Is the association between late-life morbidity and disability attenuated over time? : Exploring the dynamic equilibrium of morbidity hypothesis

Context: There is evidence suggesting that the prevalence of disability in late life has declined over time while the prevalence of disabling chronic diseases has increased. The dynamic equilibrium of morbidity hypothesis suggests that these seemingly contradictory trends are due to the attenuation of the morbidity-disability link over time. The aim of this study was to empirically test this assumption.Methods: Data were drawn from three repeated cross-sections of SWEOLD, a population-based survey among the Swedish men and women ages 77 and older. Logistic regression models were fitted to assess the trends in the prevalence of Activities of Daily Living (ADL) disability, Instrumental ADL (IADL) disability, and selected groups of chronic conditions. The changes in the associations between chronic conditions and disabilities were examined in both multiplicative and additive models.Results: Between 1992 and 2011, the odds of ADL disability significantly declined among women whereas the odds of IADL disability significantly declined among men. During the same period, the prevalence of most chronic morbidities including multimorbidity went up. Significant attenuations of the morbidity-disability associations were found for cardiovascular diseases, metabolic disorders, poor lung function, psychological distress, and multimorbidity.Conclusion: In agreement with the dynamic equilibrium hypothesis, this study concludes that the associations between chronic conditions and disability among the Swedish older adults have largely waned over time.

Putting teeth into the developmental origins hypothesis: A longitudinal study of early childhood malnutrition, enamel hypoplasia and adolescent health in Amazonian Bolivia

Thesis (Ph.D.)--University of Washington, 2016-06